Updated to work with Minecraft versions 1.21.3 to 1.21.10!
Added Barrier as possible block that can spawn as the floor when normal mode is active
Added these blocks as possible chunks that can spawn when disco chunks mode is active
Lantern
Trial Spawner
Vault
Block of Resin (1.21.4+)
Creaking Heart (1.21.4+)
Pale Moss Block (1.21.4+)
Pale Oak Fence (1.21.4+)
Pale Oak Fence Gate (1.21.4+)
Pale Oak Log (1.21.4+)
Pale Oak Stairs (1.21.4+)
Pale Oak Slab (1.21.4+)
Pale Oak Trapdoor (1.21.4+)
Pale Oak Wood (1.21.4+)
Resin Bricks (1.21.4+)
Stripped Pale Oak Log (1.21.4+)
Stripped Pale Oak Wood (1.21.4+)
Dried Ghast (1.21.6+)
Copper Bars (1.21.9+)
Copper Chain (1.21.9+)
Copper Chest (1.21.9+)
Copper Golem Statue (1.21.9+)
Copper Lantern (1.21.9+)
Copper Torch (1.21.9+)
Lightning Rod, new variants (1.21.9+)
Shelves (1.21.9+)
Added function to uninstall pack: /function ac_floor_change:ac_lib/uninstall
When /trigger chunk.change_to_block is run with nothing in the mainhand, the floor will now become barrier blocks
To help reduce lag from certain floor blocks dropping items (e.g. leaves decaying into saplings apples and sticks), a small selection of non-player-dropped items will now despawn from the world faster
Removed Sculk Catalyst as possible block that can spawn as the floor when normal mode is active, seemed to generate a lot of lag
Adjusted the "New Day" message to play as a subtitle rather than a chat message
Fixed these block types not being replaced by new blocks when a floor change was triggered
Adjusted pack install message to be shorter, and only play once

Every time a day passes, the entire floor changes to a different block.